Genetic engineering to eradicate invasive mice on islands: modeling the efficiency and ecological impacts

Abstract

Citation: Backus, G. A., and K. Gross. 2016. Genetic engineering to eradicate invasive mice on islands: modeling the efficiency and ecological impacts. Ecosphere 7(12):e01589. 10.1002/ecs2.1589Abstract. Invasive rodents are usually eradicated from islands through the application of chemical toxicants that can harm surrounding ecosystems. A recently proposed alternative involves engineering a house mouse (Mus musculus) to carry a genetic construct that would cause a majority of its offspring to be male, many of which would be sterile. Releasing these genetically engineered mice to interbreed with an invasive population would reduce the number of fertile female mice until no more remain. We constructed a mathematical model to analyze the population dynamics of eradication with this genetically engineered mouse and determined its eradication efficiency through model analysis and simulations. Because genetically engineered mice would likely have a fitness disadvantage compared to wild mice, we found that they would need to be repeatedly released into the population to ensure complete eradication. However, if genetically engineered mice have a substantial survival advantage, we determined that the genetic construct could theoretically spread and eradicate a population after a single pulsed release onto the target island or after an engineered mouse escapes to a non-target location. Also, while the species specificity of genetic engineering avoids some of the non-target impacts of traditional eradication methods, ecological impacts could manifest indirectly. We compared several metrics to estimate potential transient impacts on the ecosystem and found that there is a trade-off between the speed of an eradication and the intensity of increased disruptive ecological interactions. Together, our results can inform safe and efficient ecological practices for eradication with developing genetic engineering technology.

Identification and characterization of a Masculinizer homologue in the diamondback moth, Plutella xylostella

“…Although it remains to be determined whether a similar piRNA-based system operates in DBM, one might speculate that expression of an analogous, nucleotide recoded, PxyMasc transcript in DBM females would act as a dominant female-specific lethal effector for an fsRIDL systemprobably with fewer fitness costs to transgenic males as this is an endogenously expressed gene in this sex. If a gene drive was used to spread such a dominant female lethal at a neutral locus this would constitute a 'RIDL-with-Drive' population suppression strategy (Thomas et al, 2000): a design that has been previously modelled as significantly more powerful at population reduction than current self-limiting systems (Thomas et al, 2000;Backus and Gross, 2016;Prowse et al, 2017;Burt and Deredec, 2018). The inherent self-limiting nature of a RIDL-with-Drive system may be preferable for a pest such as DBM, which is capable of extremely long distance migrations (up to 1000 km per day; Talekar and Shelton, 1993) and for which less controllable 'global drive' designs may therefore be less appropriate (Esvelt et al, 2014).…”

Carrying a selfish genetic element predicts increased migration propensity in free-living wild house mice

“…To our knowledge, this is the first evidence of increased migration propensity of carriers of any selfish genetic element in a free-living population. Our research is particularly timely, as the t haplotype is proposed as a basis for artificial gene drive systems to eradicate house mouse populations [42,43] and behavioural differences in migration propensity between þ/t and þ/þ would need to be considered in modelling and implementing such systems.…”

Genetic characterization of invasive house mouse populations on small islands

“…This is usually effective when target animals are genetically susceptible (Howald et al 2007), as we have shown in the case on Southeast Farallon and Floreana, but non-target species are also at risk (San Francisco Bay National Wildlife Refuge Complex 2013). Gene drives are being explored as a more targeted alternative (Backus and Gross 2016; Prowse et al 2017; Leitschuh et al 2018). One proposed technique is transgenic delivery of the male sex-determining factor ( Sry ) on in the background of the t -haplotype, an autosomal segregation distorter present at low frequencies in the wild (Backus and Gross 2016).…”

“…Gene drives are being explored as a more targeted alternative (Backus and Gross 2016; Prowse et al 2017; Leitschuh et al 2018). One proposed technique is transgenic delivery of the male sex-determining factor ( Sry ) on in the background of the t -haplotype, an autosomal segregation distorter present at low frequencies in the wild (Backus and Gross 2016). This system would distort the sex ratio in favor of males and thus suppress the reproductive potential of the population, in similar manner to vector control systems recently trialled in mosquitos (Galizi et al 2014).…”